1. Technical Field
The present invention relates to a self-diagnosis circuit for use in a video display system, and more particularly, to a self-diagnostic circuit for performing self-diagnostic testing of specific electronic subsystem components within a video display system and method of implementing the same.
2. Background Art
Generally, a video display device such as a cathode ray tube (CRT) monitor for a personal computer or a television set must be tested and adjusted to its various geometrical and optical deviations and distortions for quality control on a production line. Functional parameters of the CRT displays must sometimes be preset according to buyers' requirements and the scanning dimensions on a display must be regulated to be smaller or larger than the actual size of a display if functional features are set in advance.
Traditionally, to conduct such a performance test on the CRT displays such as disclosed in U.S. Pat. No. 4,538,268 for Test-Signal Generating Device For Testing Electronic Equipment issued to Cang, a number of standard full-field video test signals in a form of geometric diagrams must first be input into the monitors so that an operator can inspect if the diagrams are distorted. If the diagrams are distorted, an operator must adjust the horizontal and vertical lines on a monitor until the diagram on the monitor is adjusted into a normal one. The video test signals may be generated by a conventional video display test pattern signal generator such as disclosed in U.S. Pat. No. 5,319,446 for Test Pattern Signal Generator issued to Emmoto. All such operations are, however, tedious and time consuming, and must be carried out manually by an operator on a production line.
More recent video display testing systems such as disclosed in U.S. Pat. No. 5,442,391 for Method And System For Testing A Cathode Ray Tube Or Like Products issued to Hung et al., use electronic cameras in lieu of an operator to read the standard test pattern from the screen of a test CRT video displays for a computer to adjust functional parameters of the tested CRT display. However, such video display testing systems are relatively bulky and inconvenient to operate. Other attempts to test CRT video displays are disclosed in U.S. Pat. No. 5,343,242 for Testing Video Equipment issued to Rowsell et al., in which external testing equipments such as oscilloscopes, signal analyzers or voltage/current measuring instruments are used to test the operational status of individual subsystem components within a CRT video display. Consequently, the conventional video display testing equipments used to test an operational status of each individual hardware components within a tested CRT video display are either unnecessarily complicated and expensive or require time consuming manual participation from an operator on a production line.
One recent video display testing system that represents a notable improvement over the traditional manual video display testing technique and the more elaborated computerized video display testing technique is disclosed in U.S. Pat. No. 5,526,043 for Automatic Video Display Testing And Adjusting System issued to Wen. In Wen '043, the automatic video display testing system is made up of a transparent mask, a main circuit board fixed to a CRT video display, a plurality of adjustable sensor mounting members to each of which is secured a sensor, and a computer system connected to the main circuit board by cable and having an operation program used for testing and automatically adjusting a CRT video display. The operation program is used to perform the testing and adjusting without manual interference as long as the transparent mask is mounted on a CRT video display with all the sensors accurately placed on a surface of a tested CRT video display for sensing a scanning light on a CRT video display in test. The automatic video display testing system of Wen '043 is, however, not capable of testing individual hardware components within a tested CRT video display. Accordingly, I believe that further improvement can be contemplated for the testing of individual hardware components within a CRT video display.